Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Diy DewHeater/Mask/Flats/Cover

Recommended Posts

Need some help with a sanity check. Have been trying to get my head around being able to cover the scope for darks, use a flat panel, and use a mask from the comfort of my living room without the constant trips in and out. It's not too bad at the moment but when there is 3 foot of snow on the ground and a clear night it wont be pleasant.

I knocked this idea up last night, and thought I could even integrate a dew heater into the holder frame. So I effectively get 4 features. I have seen the flip-flats, but wanted to keep the mechanics simple and not have to spend £300-£600 on a solution for all 4 features. Is it mad? Have I missed something obvious? It would be a little 28BYJ motor running off an Arduino nano or similar and an EL panel for the flats. Not sure how I would read the current position yet but sure that wouldnt be too tricky.

Have I missed a reasonably priced solution for this? Should I be considering a linear slide mechanism instead?

Ideas welcomed as im sleep deprived

Aim is to 3D print it so it could be made for any size. But primarily its designed to fit over the dew shield of the TS65Q

Share this post

Link to post

Share on other sites

Are you thinking of putting all the control as well as the motor at the ota end ? If so, the EL panel power supply usually needs 12v to drive its inverter, so you need to make allowances for the extra cables etc.

I'd also recommend some way to enable\disable the panel as the inverter can be quite noisy electrically, and may interfere with your other equipment.

Share this post

Link to post

Share on other sites

Looks alright to me. That little stepper motor should do the job nicely. You just need to work out w many steps to use.

Working on a method for detecting position cheaply. Which would mean it could rotate until it finds the place it should be then stop. I could calculate the steps and drive it but want to know it can work it out for itself too incase something shifts. Effectively parking with the cover over.

6 minutes ago, Dr_Ju_ju said:

Are you thinking of putting all the control as well as the motor at the ota end ? If so, the EL panel power supply usually needs 12v to drive its inverter, so you need to make allowances for the extra cables etc.

I'd also recommend some way to enable\disable the panel as the inverter can be quite noisy electrically, and may interfere with your other equipment.

I was thinking USB & 12v would run to the end of the OTA, so everything would be driven there. The panel will need to be enabled disabled by the arduino as its a combined cover for darks. How ill integrate that with APT/Ascom is beyond me at the moment but must be possible.

I was going to motorise the focuser eventually as well, and just use the bhatinov for manual changes. Im pretty sure APT has a focusing tool that measures FWHM that is supposed to be quite good but cant test until i motorise the focuser.

Share this post

Link to post

Share on other sites

I mostly use SGPro, and together with the focuser I linked to (granted you have to build it yourself), it works a treat, as Robert Brown, author, has also written an Ascom driver. It even works under Linux\Indilib\EKOS etc.

I have APT, but not tried it yet, maybe later on today as the skies are forecast to be clear again.....

Share this post

Link to post

Share on other sites

I mostly use SGPro, and together with the focuser I linked to (granted you have to build it yourself), it works a treat, as Robert Brown, author, has also written an Ascom driver. It even works under Linux\Indilib\EKOS etc.

I have APT, but not tried it yet, maybe later on today as the skies are forecast to be clear again.....

Have heard good things about SGPro - I went for APT as the learning curve seemed a little less steep and I fell in love with the plate solving goto etc. I haven't tried SGPro yet but probably should.

Im going to look into that project you linked too a little more, if it can be driven with ASCOM then APT will support it for focusing too - doing away with the bhat mask would simplify things for sure.

Share this post

Link to post

Share on other sites

I mostly use SGPro, and together with the focuser I linked to (granted you have to build it yourself), it works a treat, as Robert Brown, author, has also written an Ascom driver.

Did you build one of these yourself? I just priced the components on eBay and its £98.49 before the PCB, including motor. Not too worried about the PCB as I can build it on vero board.

Granted thats because its all coming from different sellers so theres a lot of postage built in there - but even mouser/rs/element14 the pack sizes are killing me. Where did you source your components?

Share this post

Link to post

Share on other sites

Did you build one of these yourself? I just priced the components on eBay and its £98.49 before the PCB, including motor﻿. Not too worried about the PCB as I can build it on vero board.

Granted thats because its all coming from different sellers so theres a lot of postage built in there - but even mouser/rs/element14 the pack sizes are killing me. Where did you source your components?

I'm not sure how you arrived at that cost, as mine cost a lot less, including my own design PCB's, but I also have loads of components left over from my days @ the BBC.

Share this post

Link to post

Share on other sites

After giving it some more thought and ordering the components for the myfocuserpro2 I have come up with a revised design. I have 3D printed a few iterations to get past tolerance issues etc and the EL panel I ordered fits perfectly inside the latest print, as does the 100mm disc of led difusing acrylic. This will be bluetooth/arduino controlled for raising and lowering the flap.

Im still not sure how I will do positioning - I have two pin holes in the body which I can wire to a open switch on the arduino - then when the flap is lowered enough a metal plate will complete the circuit. I wanted something a bit more elegant but this will do for this version.

Ill get some photos of the finished product once I get this hectic weekend out of the way and can work on it a little more.

Ill print a second one with a slightly larger aperature as a cover only for the guidescope.

Share this post

Link to post

Share on other sites

Hall switches and little magnets can be useful for detecting position - something I've often done.

I havent used one before so will need to get hold of one and experiment with trigger distances etc, then integrate it into the body.

The belt distance worked out at exactly a 51 tooth GT2 belt, which is a convenient size and ready to order so getting one of those dispatched to save me making a belt. HC-05 module also arrived so if I can do this over bluetooth serial with an Ard Nano that would be great for integrating as a script in APT and cutting down on some extra wires.

Share this post

Link to post

Share on other sites

Belt arrived and was too short. Must have got my calculations wrong somewhere along the line - but in all honesty I wasn't happy with the 3th printed prototype anyway.

I decided to take the opportunity to redo some of the elements of the design, namely putting a small push switch in the bottom of the OTA frame to signal when the flap is closed fully. I also wanted to beef up the swivel mechanics as it was just too... floppy... I'm now going with some teeny tiny bearings and a 5mm bolt to prevent having to drill out the bores on the pulleys. A third leg should help reinforce the hinge too as well as act as a mechanical stop.

I considered adding another sensor or switch into the top of the mount to determine when it was fully open but I think im just going to do it using a known number of steps. Eg, close until button detected, then open x number of steps.

All wires will go to a control box that will be strapped to the mount, this will then either be fed with just 12v and use bluetooth for comms or have a USB lead as well (depends how well my tests with the HC-05 module go)

Some renders until I can get round to getting the printer set up again (may not be allowed until after xmas now )

Share this post

Link to post

Share on other sites

Well having nothing but issues. Dragged the printer back out of xmas storage and its showing off. Missing layers and generally rubbish quality so struggling to get a good print. Slic3r is doing much better than Cura for supports but needs some refining to get a good finish (I may just fill, sand and paint for the final)

Tonights print has worked enough to test tolerances once more, and the final bits have been ordered for both the flaps and the focuser. New bolts and shims, and some bearings (which I have sized wrong so need to change in the final print). Also ordered some black PLA as grey isn't going to cut it for me on this I'll be building an extra (without the EL panel) for the guide scope too - no real reason to other than I can and if I ever did get an obsy set up it would be an automatic dust cover.

I built the myfocuserpro2 circuit on xmas eve and it powers up enough to test, going to build with a nema pg27 reluctantly as im concerned a nema14 wont hold the camera well enough and want the extra torque the planetary gearbox should give me. A few switches to arrive and I can print a project box and bracket for the motor.

If my maths is right (it rarely is) then the PG27 should give me 306 full steps in the CFZ which is way more than the recommended 10-20.

The MyFocuserPro2 has ASCOM support, so I assume I can integrate it into APT fairly easily. The flap will be a script of my own design though - so getting it working within the imaging plan is the next challenge in the back of my mind.

Share this post

Link to post

Share on other sites

If you've printed in PLA, you could try smoothing the finish with Acetone (I use cheapo Tesco, nail varnish remover).

As for slicer, try Prusa's edition @ https://www.prusa3d.com/slic3r-prusa-edition/ even though its targeted at their printers, but the profiles are easily configurable, I find it makes a better 'job' than Cura and even Simplify 3D.

Share this post

Link to post

Share on other sites

If you've printed in PLA, you could try smoothing the finish with Acetone (I use cheapo Tesco, nail varnish remover).

As for slicer, try Prusa's edition @ https://www.prusa3d.com/slic3r-prusa-edition/ even though its targeted at their printers, but the profiles are easily configurable, I find it makes a better 'job' than Cura and even Simplify 3D.

Might give it a go, have tried acetone smoothing with ABS with impressive results but not PLA.

I will give the prusa edition a go. I think one of my biggest issues right now is needing to recalibrate for this filament, in particular the retraction and temps.

Share this post

Link to post

Share on other sites

Shims, bearings and washers in - but still not happy. The flap mechanism works albeit a little stiff.

The issue is around the motor. Positioning it carefully in cad, with accurate models just hasn't translated into real life and the belt is sloppy. Tighten it up and its pulling the flap at an angle - realistically the hinge points are the wrong way round and the tube ring should have the outside support on it I think. The 28BYJ motor is small and compact but my mounting options are limited with the silly little tabs - I really need slots so that the position is adjustable but that means turning the motor through 90 degrees at least adding to the height.

Thinking this might be a back to the drawing board kind of job.

On a more positive note I finished soldering up the MyFocuserPro2 board and testing that. It seems to be working on larger moves although single stepping with the buttons makes the motor jump a bit too aggressively. The PG27 motor gives me plenty of steps in the critical focus zone though. 92 micron focus zone, 3.58 microns per step. So around 25 steps.

The mount bolts in to the focus lock thread underneath, and into the threads for the finder mount. So its nice and secure, hugging the tube. Motor is connected to a DB9 which will go to the control box that is currently printing as I type. The box is only temporary until I build my control briefcase which will house everything.

Disconnecting is relatively quick as the whole assembly can just slide off once the coupler is loosened, allowing a quick switch back to manual focusing (although this can be done with the push buttons too on the controller)

My 3D printer heat bed decided to let out some of its magic smoke today so trialing cold bed printing before I can continue.